Device for facilitating instrument settings



Jude 3 1926.

' D. J. MONOSMITH DEVICE FOR FACILITATING INSTRUMENT SETTINGS FiledSept. 22. 1924 2 Sheets-Sheet 1 Q /Nl E/v7-oe fia QIVIDJMIVQSMITH ATe/vEv.

1 are subject to. manual Patented June 8, 19 26.

UNITED STATES PATENT OFFICE.

DAVID J. MONOSMITH, DESPENCEB, OHIO, ASSIGNOB TO'THE HONOSMI'IH BROTHERSCOMPANY, OF SPENCER,

OHIO, A CORPORATION OF OHIO.

DEVICE FOR FACILITATING IIVSTRUMEN'I SETTINGS.

Application filed September 22, 1924. Serial No. 788,992.

densers, which applications are also illustrated in the accompanyingdrawings.

I will nowdiscuss briefly the advantages of this device. Taking'thespecific case of a variable electrical condenser for radio use, weoften find that the bearings of the instrument do not operate smoothly,but operate with a jerky unsteadymovement, particularly for very slightmovements, making fine tuning very difficult. The bad effects of thisirregular movement can be obviated by adding a resistance to movementthat increases rapidly as the velocity of the movement increases. Inthis invention, I make use of a peculiar property of certain types ofresistance contacts,

slippage, increases as the rate of slippage increases, but not to theextent shown by a very viscous liquid, which is described and claimed inmy patent application Serial No. 6 714,261, filed May '19, 1924.However, the resistance to increase in speed of movement between thecontact surfaces is sufiicient to be of material assistance in the fineadjust itment of'the instrument to which it is applied. There is adecided practical advantage in the use of specialresistance'surfacesover that in the emplo ent of a very viscons liquid,one reason ing that avery viscous liquid has a tendency to harden andafter a time to become inoperative, and another is that the viscousliquid has a high temperature coeflicient of viscosity which is adetriment.

I do not lay any particularstress upon whether the action of theresistance elements is called a lubricating action or a friction action.Tosome it may appeal as one action the resistance of which, to-

and to others as the other action. The principle of my improved device,in the abstract, is an mcreasing resistance to an increasing rate ofslippage, no matter what the concept of the action may be to anyparticular mind;

The several figures illustrate various modifications involving the samegeneral principle of a. resistance sliding contact between two surfaces,one of which is smooth or polished and the other formed of some Imaterial which affords a smooth steady slippage, for instance, a surfacecoated with zinc 'ste'arate. As an alternate construction, two

prepared surfaces face to face may be used instead of one preparedsurface and onesmooth surface,'depending in this instance how the twosurfaces are prepared, that is, at least one of the prepared surfacesshould be smooth as, for instance, smooth card board coated with zincstearate.

The annexed drawings and the following description set forth in detailcertain means embodying my invention, such disclosed means constituting,however, but afew of the various forms by which the principle of theinvention may be illustrated.

In said annexed drawings: Figure 1 represents a vertical longitudinalsection through a graduated dial andpanel to which one form of myinvention has been applied, and showing a fragmentof the shaft of theinstrument to be adjusted or.

tuned Figure 2 represents a vertical f section through a prepared discand a spider used in the assembly shown in Figure 1;

Figure 3 represents an elevation. of the same prepared disc;

Figure 4 represents an elevation of the same spider; v p

Figure 5 represents a vertical longitudinal section-of a graduated dialand the instrument to be adjusted or tuned, to which has been applied asecond form of my invention;

Figure 6 represents a vertical section of two s iders and a prepareddisc used in the assem ly shown in Figure 5; i

Figure 7 represents an elevation of the disc shown in Figures 5 and 6;

Figure 8 represents an elevation of one of the spiders used in theassembly shown in Figures 5 and 6;

Figure 9 represents a vertical, longitudinal section through a graduateddial and panel to which a third form of my invention has been applied,and showing a fragment of the shaft of the instrument to be adjusted ortuned;

Figure 10 represents a vertical section through the prepared disc andspider in the assembly shown in Figure 9;

Figure 11 represents an elevation of the spider shown in section inFigures 9 and 10;

Figure 12 represents a plan section on line XII-XII of Figure 11;

Figure 13 represents a longitudinal ver tical section of an instrumentto be tuned, showing a form of my improved device as an attachmentinstalled at the rear of the -instrument, a graduated dial being shownin elevation;

Figure 14 represents a vertical longitudinal section through theprepared disc and spider with shaft and attached collar, used as shownin the assembly drawing of Figure 13;

Figure 15 represents a vertical cross section on line XXL-XV of Figure14;

Figure 16 represents a vertical longitudinal section through aninstrument to be tuned, showing a second form of the improved deviceattached' to the rear end of the shaft of the instrument,the graduateddial being shown in elevation;

Figure 17 represents an end elevation of the reslstance device taken atright anglesto the view shown in Figure 16;

Figure 18 represents an enlarged plan section on the line XVIII-XVIII ofFigure 16; I v

Figure 19 represents an enlarged vertical cross-section taken on theline XIXXIX, Figure 16; and

Figure 20 represents a perspective of one of a pair of block elementsshown in Figure 19.

I shall give a brief description of the prepared surface before goinginto detail as to the construction and operationof the device. Thedesired surface may be prepared from a number of materials and in alarge variety of forms. My preferred method is to take smooth card boardand coat the surface with zinc stearate or a mixture of zinc steal-ateand finely powdered graphite. While the preferred materials are asdescribed above, almost any material having a reasonably smooth surfacemay be coated with, for instance,rzinc stearat'e, and give very goodresults The object is to provide a surface that will produce a smoothslippage and offer increasing resistance as the speed of slippageincreases. This increase in the resistance ceases upon the applicationof a certain maxinnunforce 'to the operating knob 12 of the instrumentbeing adjusted. The increase in resistance the dial 13 is also '29 ofpanel 15.

from the starting torque (the force necessary to overcome the deadfriction) to the velocity of rotation of the operating knob 12 forordinary coarse adjustment is about four-fold, when the device is inordinarily 7 good working condition. When the device is working withbetter than average results, the increase in resistance, over the statedrange, may be as high as ten-fold.

Figure 1 represents a graduated dial 13 made ofa non-metallic materialwith a cy; lindrical hub or insert 35 for the purpose of receiving a setscrew 30. Hub 35 ro trudes from the inner surface of the dial intochamber 27 sufficiently to,serve as a guide or retainer for a spider 23.Spider 23 is provided with a central circular opening 26, this openingallowing the end of hub 35 to pass through with a loose fit, thusholding spider 23 in place when the device is assembled. The innersurface of rovided with an annular shoulder to ho d a circular washer 6in place, said washer having a special surface 6' prepared with zincstearate, as hereinbefore described, all as shown in Figure 1. Thespider 23 is preferably a stamping of some springy material as thinsheet spring brass or steel and is formed with several arms 24. One sideof the inner circular flat body part of the spider is smooth or polishedand is designated'by numeral 25. The arms or spring members 24 of thespider are bent at an angle to the body part and away from the smoothsurface 25, as shown in Figure 2. Any number of arms to the spider maybe used, but a spider of eight arms is here illustrated since a largenumber of arms reduces the distortion of the surface 25, due to thebetter distribution of the strain of the arms on the inner disc portionof the spider. The device as illustrated in Figure 1 is assembled byplacing washer 6 in position in chamber 27 of dial 13 with preparedsurface 6' exposed no and then placing the spider 23 with the smoothsurface 25 in contact with the prepared surface 6 of the washer 6, theninserting the shaft 1 of the instrument in hub 35 and pressing dial 13intoposition compressing or tensioning springs 24 and holding dial 13 inpositlon by tightening set screw 30. Spider feet 34 in contact withsurface 29 of panel 15 do not, in the ordi-' nary use of the device,slip on the surface The adjustment efiect is secured by the action ofsmooth surface 25 slipping over the prepared surface 6', these twosurfaces being held in contact by the tension of springs 24. The correctpressure of contact is determined by experiment, but in practice, thereis a" wide latitude of pressures that will give satisfactory operation.The peculiar property of the resistance action between the surfaces 6and is that the resistance increases rather rapidly with slight increaseof the rate of slippage between the said surfaces, but this resistancedoes not increase indefinitely with the increased rate of slippage butsoon reaches a maximum so that both the coarse or quick adjustment andthe precise or fine adjustment of the device can be effected through theslipping of the surfaces 6' and 25 without any auxiliary action of thefeet 34 slipping on the surface 29 of the panel 15, as made use of in mypatent application Serial No. 714,261, filed May 19, 1924. To reiteratethis action in other words: A strong torque on the dial 13 through theturning of the integral finger knob 12 will cause the dial 13 to rotaterapidly for rough adjustment, so that both precise and quick adjustmentsare effected by the slippage of surface 25 over surface 6' without anyspecial auxiliary coarse or'quick adjustment means. It may be noted thatin some instances the spider feet 34 will slip when the dial is rotatedrapidly and an extreme resistance is offered between the preparedsurface 6' and the smooth surface 25, but'this is merely incidental andnot a vital part of the invention nor is it essential to the properoperation of the device. The foregoing sentence applies also to theconstruction shown in Figure 5 but not the other constructions shown inFigures 9, 13 and 16. Figure 5 represents a modification of the formshown in Figure 1. In this form two spiders 23 and 23 are used with thesmooth surfaces 25 facing each other with washer 6 having preparedsurfaces 6 compressed between the smooth surfaces 25. The feet 34 ofspider 23. press against the inner surface of the dial 13 and the feetof spider 23 press against panel 15. Spider 23 rotates with the dial 13and spider 23 remains stationary, the slippage taking place on thesmooth surfaces 25 and the repared surfaces 6' of the washer 6. T isform can also be used with only one prepared surface 6 on the washer 6.

The construction shown in Figure 9 still further differentiates from theform shown in Figure 1. In Figure 9 the spider 23 is rigidly fastened toinsert 35 and positively rotates with the dial 13. The outer ends ofarms 24, shown particularly in Figure 12, have smooth or polishedsurfaces 33 which, when assembled, press against the prepared" surface6' of disc 6. Disc 6 is circular and somewhat larger in diameter thanthe spider 23 and is mounted over shaft 1 and against surface 29 ofpanel 15 with the prepared surface 6 facing the dial 13. Disc 6 may besecured to panel 15 or left free to rotate. In the latter case it willusually cr'eep under the action of the spider feet 33 on the surface 6'as the dial 13 is rotated. The arms 24 of spider 23 are bent throughpanel 15. In this" modification the device is attached at the rear endof the condenser shaft 1. Otherwise, the construction shown in Figure 13is very similar to the one shown and described under Figure 9. The rearshaft bearing 14 is expanded at the rear end to form a plate 14. Spider23 is rigidly fastened, as by solder, to collar or hub 36. Spiderarms 24are bent as indicated in Figure 14 and the resistance contact feet 33are smooth or polished. To assemble the device: Slip washer 6 over shaft1, place in contact with, or fasten to flange 14 with prepared or coatedface 6 away from flange 14'. Pass collar 36'over shaft 1 and pressspider'member into position with the desired pressure contact betweenresistance surfaces 6 and 33 and lock collar or hub 36 on shaft 1 withset screw 37. The characteristics of operation ofthis modification ofthe device are practically the same as described under Figure 9.

Figure 16 represents a vertical longitudi nal section through a variableelectrlc condenser with a graduated dial 13 attached to the condensershaft 1 which extends through panel 15. This modification of the deviceis also attached. at the. rear of the condenser I shaft 1. In thisdesign the resistance surto fit the width of'groove 38 as indicated inthe several Figures 16171819-and 20. Resistance blocks 18 and 18are'rectangular in cross-section and one face is slightly less inwidththan the width of the groove 38 and in this face is out a transverseseg- I 'mental circular groove 39 slightly larger than the convexsurface of groove 38111 collar 17. In the opposite face of block 18 iscut a small longitudinal groove 20 to receive compressionrods 21. Inorder to provide the special resistance surface 6; the concavetransverse segmental grooves. 39 in resistance blocks 18 and 18 arelined with some material as cork or leather 6 and the surface 6' whichcomes in contact with convex surface 25 is treated with some specialresistance substance, as zinc stearate. The resistance surfaces 6' and25 are held. in contact by the action of compression rods 21 which restin grooves 20 of blocks 18 and 18'. These rods 21 also serve to preventblocks 18 and 18 from rotating with the shaft 1. compression rods 21provides means for con? trolling the amount of resistance betweenresistance surfaces 6 and 25. The com ression rods 21 are anchored toframe 9 of the variable condenser by screw 8, the condenser being spacedby members 16 from the panel 15 to which it is attached'by screws (notshown). I

All of these several modifications ofthc device. give substantially thesame control over the adjustment of the graduated scale or dial 13. Themodifications shown in Figures 1, 5 and 9 have the advantage, to a greatextent, of compensating for any looseness in the bearings of theinstrument to be tuned and can readily be-applied to an instrument thathas been installed, and also are less expensive to manufacture.

I wish to direct particular attention to the advantage of the springelement whereby the sliding contact surfaces are held together. Thisfeature, together with the set screws provided as shown, has twoparticular advantages:

. (a) Compensates for imperfections in the mechanism so as to give asubstantially constant pressure to the sliding surfaces in contact; and

(6) Provides means for adjusting the amount of contact pressure betweenthe sliding members.

Advantage (b) will be readily understood, and asregards advantage (a), Iwish to point out that, for instance, the shaft'of the condenser -mightnot be at exact right angles to the panel, or the panel might be-warped, in the form of devices shown in Figures 1, 5, 9, and 13, sothat the smooth action of the device could not well be maintainedwithout the compensation provided by the spring spider. V

Incorporated in the various figures and the description, is a fibrouselement, given as a preferred construction, designated by the numeral 6,on which the special resist,- ance material or compound, as zincstearate,

v is coated. It is quite obvious that the zinc stearate, or any otherreparation or compound, to form the sur ace 6, may be held in place bysome other means or simply coated on the surface opposed to the smoothsurface 25 without in the least departing from the fundamental'principleof the invention. The fibrous'element 6 is given only as a convenientmeans of holding the special resistance surface coating in place, and isnot to be construed as necessarily the only means of accomplishingthisfunction.

My invention also includesseparate selfcontained units of devices forfacilitating instrument settings, which units can readily Adjustabletension screw 22 onbe applied to such instruments that have already beeninstalled, wherein the unit comprises engaging resistance elements whichhave the properties noted of offering only a very slight resistance toslow, easy movements of the setting means and a rapidly increasingresistance as the speed is accelerated up to a certain maximum, afterwhich the resistance is substantially constant. Such. resistanceelements with said properties are adaptable for both fine and roughadjustments and in thisrespeet differ from the-viscous liquid devicedescribed and claimed in my application Serial No. 714,- 261, filed May19, 1924, wherein an auxiliary friction element is utilized for therough setting. Wherever zinc stearate is specified in the followingclaims, it is intended thereby to cover the equivalents of zinc stearatefor the purposes noted, such as other stearates, and probably a verylarge number of other substances, that will give this increasingresistance to an increasing rate of slippage, with which I have notexperimented or at present am not aware.

What I claim is:

1. A device for facilitatin instrument settings, consisting of movabemeans for ments of the latter, said resistance device including engagingelements adapted to offer' only a very slight resistance to slow, easymovements of the changing means and a rapidly increasing resistance asthe speed is accelerated up to a certain maximum, beyond which theresistance is substantially constant.

2. A device for facilitatin instrument settings, consisting of movab emeans for changing t e instrument setting;,and a resistance devicerelated to the changing means so as to offer resistance to the movementsof the latter, said resistance device including engaging elementsadapted to offer, for fine adjustments, only a very slight resistance toslow, easy movements of the changing means and a rapidly increasingresistance as the speed is accelerated, and to offer, for roughadjustments, a substantially constant resistance.

' 3. A device 'for facilitating instrument settings, consisting ofmovable means for changing the instrument setting; and a resistancedevice related to the changing means-so as to ofl'er resistance to themovements of the latter, said resistance device including elementshaving surfaces engaging through themedium of a zinc stearate coating. I

4. A device for facilitating instrument settings, consisting of movablemeans for so as to be capable of slipping upon said connected elements,said elements engaging through the medium of surfaces treated so as tooffer only a very slight resistance to slow, easy movements of thechanging means and a rapidly increasing resistance as the speed is acceerated up to'a certain'maximum, beyond which the resistance is substantially constant.

5. A device for facilitating instrument settings, consisting ofxmovablemeans for changing the instrument setting; means for indicating theamount of said change; and a resistance device related to the changingmeans so as to offer resistance to the movements of the latter, saidresistance device.

comprising an element connected to the changin means and an engagingelement indepen ent of the changing means so as to be capable ofslipping upon said connected element, said elements engaging through themedium of a'zinc stearate coating.

6. A device for facilitating instrument settings, consisting of a dial;a shaft adapted to be actuated by the movements of the dial; a supportfor the instrument to be adjusted, said dial being formed with aresistance surface; a resistance element; and means causin said elementto adhere to said support by%riction, said element also having aresistance surface formed adjacent .the surface upon said dial, saidopposed surfaces engaging and being treated so as to offer only a veryslight resistance to slow, easy movements of the dial and a rapidlyincreasing resistance as the speed is accelerated up to a certainmaximum, beyond which the resistance is substantially constant.

.7. A device for facilitating instrumentsettings, consisting of a dial;a shaft adapted to be actuated by the movements of the dial; a supportfor the instrument to be adjusted, said dial being formed with aresistance surface; a resistance element; and

means causing said element to adhere tosaid support friction, saidelement also having a resistance surface formed adjacent the surfaceupon said dial, said op osed' sur; faces engaging and one of them beingcoated with zinc stearate and the other ground smooth to facilitate aslipping action.

8. Adevice for facilitating instrument settings, consisting of a dial; ashaft adapted to be actuated by the movements of the dial; a support forthe instrument to be adjusted; a resistance element; means causing saidelementto adhere to sa d support by friction, a chamber being providedbetween said dial and said support within which said resistance elementis contained; and a second resistance element adapted to be actuated bythe movements of the dial and formed with a surface coated with zincstearate, said first-named resistance element being formed with asurface engagin the coated surface of said second-name resistanceelement and ground smooth to facilitate a slipping action.

9. A device for facilitating instrument settings, consisting of a dial;a shaft ada ted to be actuated by the movements of the ial; a supportfor the instrument to be adjusted; a resistance element; means causingsaid element to adhere to saidsupport by friction; and a secondresistance element secured to said shaft, said resistance elementsengaging through the medium of surfaces treated so as to offer only avery slight re sistance to slow, easy movements of the changing meansand a rapidly increasing resistance as the speed is accelerated up to acertain maximum, beyond which the resistance is substantiall constant.

10. A device for faci itatinginstrument settings, consisting of a dial;a shaft adapted to be actuated by the movement of the dial; a supportfor the instrument to be adjusted; a resistance element; means causingsaid element to adhere to said support by friction; and a secondresistance element secured to said shaft, said resistance elementsengag' g through the medium of a zinc st'earate coating.

11. A unit of a device for facilitating instrument settings, comprisinresistance elements having engaging sur aces treatedso as to offer onlya very slight resistance to slow, easy movements of one surface upon theother and a rapidly increasing resistance as the speed is accelerated upto a certain maximum, beyond which the resistance is substantiallyconstant.

12. A umt of a device for facilitating in- 13. A unit of a device forfacilitating instrument settings, comprising a pair of resistanceelements having engaging surfaces, one of said engaging surfaces beingcoated with zinc stearate and the other surface ground smooth tofacilitate a slipping action.

14. A device'for facilitating instrument settings, consisting of movablemeans for changing the instrument setting; a' first member secured tothe changing means; a stationary member; a second member adapted toslide upon said stationary -member; and means causing said second memberto adhere by friction to said stationary member below an extreme amount.of applied force, a surface of said first member being ad'acent asurface of said second member, sai surfaces engaging through the mediumof a coating adapted to offer only a very slight resistance to slow,easy movements of the changing means and a rapidly increasing resistanceas the speed is accelerated up to a certain maximum, beyond which theresist ance is substantially constant.

15'. A device for facilitating instrument settings, consisting ofmovable means for changing the instrument setting; a first membersecured to the changing means; a stationary member; a second memberadapted to slide upon said stationary member; and means causing saidsecond member to adhere by friction to said stationary member below anextreme amount of applied force, a surface of said first member beingadjacent a surface of said second member,

4 said surfaces engaging through the medium of a zinc stearate coating.

16. A device for facilitating instrument settings, consisting of a dial;a shaft adapted to be actuated by the movements of the dial; a supportfor the instrument to be adjusted, a chamber being provided between saiddial and said support; .a spring spider disposed within said chamberwhose arms adhere to the support below an extreme amount of appliedforce; a resistance element adapted to be actuated by the movements ofthe dial, the body of the spider and a surface of said element engagingthrough the medium of a coating adapted to offer only a very slight,resistance to slow, easy movements of the changing means and a rapidlyincreasing resistance as the speed is accelerated up to acertain'maximum, beyond which the resistance is substantially constant.

17. A device for facilitating instrument settings, consisting of a dial;a shaft adapted to be actuated by the movements of the dial; a supportfor the instrument to be adjusted, a chamber being provided between saiddial and-said support; a spring spider disposed within said chamberwhose arms adhere to the support below an extreme amount of appliedforce; a resistance element-adapted to be actuated by the movements ofthe dial, the body of the spider and a surface of said element engagingthrough the medium of a zinc stearate coating.

18. A device for facilitating instrument settings, consisting of a dial;a shaft adapted to be actuated by the movements of the dial; a supportfor the instrument to be adjusted,

- a chamber being provided between said dial and said support; a springspider disposed within said chamber whose arms adhere to the supportbelow an extreme amount of applied force; a resistance element adaptedto be actuated by the movements of the dial and having a surfaceextending into said chamber and engaging the body of the spider, saidsurface being formed with a device including elements having surfaces 1action.

19. A. unit of a device for facilitating instrument settings, comprisingresilient resistance elements having engaging surfaces treated so as tooffer only a very slight resistance to slow, easy movements of onesurface upon the other and a rapidly increasing resistance as the speedis accelerated up to a certain maximum, beyond which the resistance issubstantially constant.

20. A unit of instrument settings, comprising adjustable resilientresistance elements having .engaging surfaces treated so as to offeronly a very slight resistance to slow, easy movements of one surfaceupon the other and a rapidly increasing resistance as the speed isaccelcrated up to a certain maximum, beyond which the resistance issubstantially constant..

21. A unit of a device for facilitating instrument settings, comprisingresilient resistance elements having surfaces engaging through themedium of a zinc stearate coating.

22. A unit of a device for facilitating instrument. settings, comprisingadjustable resilient resistance elements having surfaces engagingthrough the medium of. a zinc a device for facilitating slow, easymovements of the changing means and a rapidly increasing resistance asthe speed is accelerated up to a certain maxis mum, beyondwhich theresistance is substantiallyconstant.

24. A device for facilitating instrument settings, consisting of movablemeans for changing the instrument setting; and a resistance devicerelated to the changing means so as .to offer resistance to themovements of the latter, said resistance device including adjustableresilient engaging elements adapted to offer only a very slig tresistance to slow, easy movements of the changing means and a rapidlyincreasing resistance as the speed is accelerated u to a certainmaximum, beyond which the resistance is substantially constant.

engaging through the medium of a zinc -ance to the movements of thelatter, said steal-ate coating. resistance device including elementshaving 26. A device for facilitating instrument surfaces engagingthrough the medium of 1 settings, consisting of movable means for a zincstearate coating.

7 F changing the instrument setting; and an Signed by me this 17th dayof September;

adjustable resilient resistance device related 1924-. a to the changingmeans so as to offer resist- I DAVID J. MONOSMITH.

